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New Report: Forest Protection Promotes Clean Water

NEW YORK, NY (February 8, 2024)—The Open Space Institute (OSI) today released a new report quantifying the benefits of forest protection on water quality, with strategies and practical tools to ensure clean water programs can more effectively engage forest protection to achieve their goals.

The publication, Protecting Forests for Clean Water: Findings from A 10-year Initiative to Promote Best Practices Across the Land Conservation Field, contains findings derived from a water quality grant initiative that protected 21,000 forested acres in the Delaware River Watershed across New Jersey, New York, and Pennsylvania between 2013 and 2023.

“While we know forest protection supports clean water, we need the data that makes that case clear to decision makers,” said Abby Weinberg, OSI’s Senior Director of Research. “Thanks to the creativity of our scientific partners, we were able to develop new approaches and recommendations that allow water utilities, land protection leaders, and agencies to connect the dots between forest protection and clean water, opening the door for greater collaboration and impact across sectors.”

The report synthesizes a four-part evaluation of the Delaware River Watershed Protection Fund that OSI administered as part of the Delaware River Watershed Initiative (DRWI). It focuses on relevant findings for water utilities, government agencies, foundations, and land protection practitioners, and advances data-based insights about how protection and proper management of forests can support clean water goals including reduction of contaminants and health of aquatic life.

Key findings include:

  • Forests keep water clean. Stream sampling studies found nitrogen levels spiked when forest cover levels fell below 66 percent. When forest cover is maintained at 70 to 90 percent or greater, streams and rivers stay healthier and cleaner, and wildlife thrives.
  • Protecting forests along streams filters pollutants from the surrounding landscape. The land protected by DRWI grantees filters and reduces about 1,680 pounds of total nitrogen annually, with rates increasing if development occurs nearby.
  • Allowing protected land to return to forested conditions results in quantifiable reductions in pollutants. More than 600 acres of the land protected by the fund were returned to forested conditions, which resulted in 4,070 pounds of total nitrogen exported annually from these areas.
  • In largely forested headwaters, loss of forest cover was most strongly correlated with reductions in macroinvertebrates, a key water quality indicator, rather than increases in upstream farmland or development.
  • Across the 21,000 acres protected, land protection resulted in the avoidance of an estimated $57 million in total stormwater capital costs and $6 million in annual maintenance costs for projected development—more than three times the cost of the land protection itself.

The Delaware River Watershed Initiative is a $150 million effort capitalized by the William Penn Foundation that has brought together more than 50 partners from nonprofit organizations, public and private foundations, land trusts, higher education, and related fields to protect and restore water quality in the Delaware River Basin, the source of drinking water for more than 15 million residents of Trenton, Philadelphia, Wilmington, and New York City.

“From the beginning of the Delaware River Watershed Initiative, the William Penn Foundation has looked to OSI’s leadership to translate science into practice. Their assessment shares that work with the broader field,” said Stuart Clarke, Program Director, William Penn Foundation. “Land protection has been under-utilized as a tool for protection of clean water in part because it is challenging to measure and quantify impacts on water quality. This new data will allow communities and agencies to be more strategic in land protection investments for improved water quality.”

“This report contributes to our understanding of the critical role that forests, wetlands, and other natural areas play in protecting and restoring waters to support healthy ecosystems and human communities,” said Dave Arscott, Research Scientist and Executive Director of Stroud Water Research Center. As the research lead for the modeling components of the study, Arscott noted, “The research findings and lessons developed with OSI provide a roadmap for how land trusts, states, and other partners can better integrate land protection in clean water programs. In many cases, water quality reflects land use practices. This report provides a means for integrating programs that are focused on either of these precious and limited resources. The project team expects the report will benefit existing and future land conservation programs.”

In addition to providing new data on water quality across the preserved acres, the Protecting Forests for Clean Water report offers new methods for assessing how land protection benefits water quality. It also recommends next steps for supporting the integration of land protection with clean water programs.

Learn more and access the report here. The Delaware River Watershed Protection Fund and this report were funded by the William Penn Foundation. Research was conducted by partners at the Stroud Water Research Center, the Academy of Natural Sciences of Drexel University, and Shippensburg University Center for Land Use and Sustainability.

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